The effect of maternal separation on the expression of glucocorticoid receptor and doublecortin in brain regions of young mice

Abstract

Objective To observe the effect of maternal separation(MS)on the expression of glucocorticoid receptor(GR)and doublecortin(DCX)in hippocampus and prefrontal cortex of young mice. Methods Fifteen pregnant mice were randomly divided into 5 groups: the experimental group(3 d, 7 d, 14 d, 21 d)and the control group, n=3 in each group. Neonatal mice in experimental group were separated from mother for 3 h once a day, and the mice in control group were caged with mother without any processing after birth. All mice were weaned in postanal day 23. Separating female and male mice, and the male mice were killed and the brains were taken in postanal day 42. The expression and distribution of GR and DCX in hippocampus and prefrontal cortex were determined by immunohistochemical staining and Image J image analysis technique. Results The average optical density values of GR positive cells in hippocampus and prefrontal cortex, the average optical density values of DCX positive cells in hippocampal dentate gyrus subgranular zone in 3 d, 7 d, 14 d and 21 d group were(GR in hippocampus: 3 d((0.332±0.054)OD/μm2, 7 d(0.258±0.045)OD/μm2, 14 d(0.197±0.043)OD/μm2, 21 d(0.164±0.053)OD/μm2), (GR in prefrontal cortex: 3 d(0.356±0.043)OD/μm2, 7 d(0.278±0.041)OD/μm2, 14 d(0.220±0.039)OD/μm2, 21 d(0.157±0.034)OD/μm2)and(DCX in hippocampus: 3 d(0.193±0.020)OD/μm2, 7 d(0.146±0.033)OD/μm2, 14 d(0.110±0.032)OD/μm2, 21 d(0.060±0.017)OD/μm2)were lower than those in control group, which showed a decreasing trend with the increase of seperation time, and the average optical density values in 7 d, 14 d and 21 d group were obviously lower than those in control group(P<0.05). The average optical density values had statistical significance among the experimental groups(P <0.05). Conclusion MS can cause the decrease of GR in hippocampus and prefrontal cortex and reduce neurogenesis in the hippocampal dentate gyrus subgranular zone in young mice. It shows that the longer the seperation time, the greater the effect on hypothalamic-pituitary-adrenal(HPA) axis and neurogenesis. Key words: Maternal separation; Hippocampus; Prefrontal cortex; Glucocorticoid receptor; Doublecortin